1. Field of the Invention
The present invention relates to processes for purifying anthracyclinone glycosides by selective adsorption on resins.
2. The Prior Art
It is extremely desirable to have a highly specific method for obtaining anthracyclinone glycosides in a substantially pure form. This is so because in both the fermentative production processes and synthetic preparation processes the amount of organic and inorganic impurities present in the crude product is particularly high and averages from 12% to 25%.
The conventional methods of purifying these glycosides that have been hitherto used in known purification techniques involve the extraction of the crude produce with chlorinated solvents and subsequent washing with buffers. These techniques however lead to a final product in which the impurity percentage, although considerably lowered, is in the range of between 4.5 and 5.0%.
While such a level of impurity might be generally deemed acceptable, under certain circumstances it is not acceptable when considering the particular sensitivity of the anthracyclinone glycoside molecule to physical handling and chemical agents. All of this stimulated our interest in the search for an improved purification method which would enable us to obtain a substantially pure final product. Bearing in mind the particular clinical use of the anthracyclinone glycosides as antitumor agents, and the related problems of dosage and toxicity, the need for maximum elimination of impurities (which are generally highly toxic) is evident.